1 We used to think the moon was as dry as dust. But NASA has found that deep inside the Cabeus crater, there is water in the form of ice. How much water is there? Enough to fill 1,500 big swimming pools!2 The Cabeus crater is near the moon's south pole. The crater is so deep that light from the sun never reaches the bottom of it. Scientists estimate that the crater holds a billion gallons of frozen water!3 Why is this important? Water is heavy, and it would be expensive for spaceships to carry enough of it to last for a long space journey. But if there's water on the moon, spaceships could stop there to fill up with it.